Imaging diagnosis which have been performed in the past involve inserting an ultra-sound catheter having an imaging function into, for example, a blood vessel of a cardiac coronary artery or into a vascular channel of a bile duct.
The imaging diagnostic apparatus can be an intra vascular ultra-sound diagnostic apparatus (Intra Vascular Ultra Sound: IVUS). Generally, an intra vascular ultra-sound diagnostic apparatus includes a probe, installed with an ultrasonic transducer, that is scanned radially in the inside of a blood vessel. A reflection wave (ultra-sound echo) reflected by biological tissue of a lumen (e.g., blood vessel lumen) is received by the same ultrasonic transducer, and thereafter, a process of amplification, detection or the like is applied and a cross-sectional image of a blood vessel is created based on the strength of the produced ultra-sound echo.
An optical coherence tomography diagnostic apparatus (Optical Coherence Tomography: OCT) has also been utilized as the imaging diagnostic apparatus. The optical coherent tomography diagnostic apparatus is an apparatus in which a probe, installed with an optical fiber attached to a probe provided with an optical lens and an optical mirror at its distal end, is inserted into the inside of a blood vessel, light is illuminated in the blood vessel while radially scanning the optical mirror which is arranged on the distal side of the optical fiber and a cross-sectional image of the blood vessel is created based on reflection light from biological tissue.
There has relatively recently been proposed an imaging diagnostic apparatus using an optical frequency domain imaging method (Optical Frequency Domain Imaging: OFDI) which is evaluated as a next-generation OCT.
Japanese Unexamined Patent Application Publication No. 2009-240710 describes a probe for insertion into a living body, forming part of an intra vascular ultra-sound diagnostic apparatus. This probe for insertion into a living body is provided with a metal tube formed with a spiral slit as a reinforcement layer in a sheath inserted into the living body.
The probe for insertion into a living body which is used for the OCT or the OFDI includes a sheath and a shaft for data acquisition. An image is obtained by rotating the shaft for data acquisition at relatively high speed in the sheath and is moved to the proximal side while being rotated. When inserting the probe into a guiding catheter, it sometimes happens that a kink occurs at a proximal portion of the sheath. In particular, when rigidity at the proximal portion of the sheath becomes too high, steerability decreases during insertion into the guiding catheter and it becomes relatively easy for a kink to occur.
Consequently, with respect to the probe for insertion into a living body described in Japanese Unexamined Patent Application Publication No. 2009-240710, steerability is improved by increasing the flexibility on the distal side of the probe which is accomplished by increasing the slit density on the distal side of the reinforcement layer (total surface area of slit portion which exists for a predetermined unit length in the axial direction of the reinforcement layer) as compared to the slit density of the center portion. The occurrence of kinking is reduced, yet the proximal portion of the sheath exhibits steerability, by imparting a certain degree of flexibility to the proximal portion by virtue of the slit density on the proximal side of the reinforcement layer being less than the slit density of the center portion.
When the density of the slit at the proximal side is increased compared with the slit density of the center portion of the reinforcement layer in the manner described in Japanese Unexamined Patent Application Publication No. 2009-240710, rigidity decreases on the proximal side of the reinforcement layer, and there is a possibility that a crack will occur at the termination end on the proximal side of the slit.